Sources of commercially available cyanine dyes that fluoresce in the long visible / infrared spectrum are severely limited and are prohibitively expensive for many research establishments. The aim of this phase I project is to introduce a new class of long wavelength cyanine fluorescent dyes that contain a more suitable component for essential water solubility in place of the existing problematic sulfonic acid groups. The new dyes will contain the highly fluorescent cyanine dye skeleton allowing them to perform as well or better than existing cyanine dyes. Applications include fluorescence polarization, infrared imaging, fluorescence-based drug discovery assays and photography. There are 4 specific aims: I. To design and synthesize the new dyes (the designing part is almost complete). 2. To fully characterize the fluorescence and physical properties of the new dyes. 3. To activate molecular handles on the dyes to allow for conjugation to proteins, etc. 4. To perform a model fluorescence polarization binding study to demonstrate high dye sensitivity. PROPOSED COMMERCIAL APPLICATIONS: Commercial applications of these new dyes include: fluorescence polarization assays, fluorescence assays, fluorescence resonance energy transfer (FRET) assays, enzyme quenching assays, tumor imaging, tissue imaging, whole body imaging and photography. Phase II work will involve synthetic and fluorescence optimization and the development of commercially available labeling kits.